Aeromedical Forum

OK, let’s get one thing straight. Marijuana use is incompatible with flight safety. If you’re stoned, find yourself a bag of munchies and watch some Big Bang Theory reruns. Don’t even think of getting near anything with an operable airfoil!

That being said, the reality of general aviation is that not all pilots are Eagle Scouts. Marijuana is the most commonly used illicit (in some states) drug. In a recent survey, more than 16 million Americans admitted to using marijuana in the previous month. Over 104 million Americans have used marijuana during their lifetime -- although over half say they didn’t inhale.

The active ingredient, tetrahydrocannabinol (THC) is bound to receptors in the brain creating the drug’s psychoactive effects. It seems that American, or perhaps Mexican agricultural ingenuity has improved the yield of the plant.

Back in the good old days of the ‘70’s, THC concentrations ranged from 1 to 3 percent. By 2005 Tijuana Gold was running an 8 percent THC level. More potent varieties such as sinsemilla may contain nearly twice as much THC. Hashish which is dried cannabis resin may pack an even more potent punch. No wonder things in the Middle East are never resolved.

When smoked, the psychoactive effects of marijuana occur almost immediately, usually disappearing within three to six hours. If weed is eaten, however the onset of effect is slower but the drug can persist in fat cells in the body for several weeks.

This can be detected by drug screening either of a urine sample or more sensitive blood testing. Effects of THC include a sense of well-being and friendliness. (Woodstock lives!) Increased appetite, a distorted sense of time and impaired short-term memory are common. (Care to try flying vectors to join the localizer?) Regular use tends to increase tolerance. Some heavy users experience withdrawal symptoms including irritability, difficulty sleeping and anxiety.

Some recent studies have suggested that use of marijuana particularly during adolescence may increase the likelihood of developing a mental disorder such as schizophrenia in later life. The other drawback of inhaled marijuana is the tar and carbon monoxide contained within the smoke. It’s said to be three to five times more than that from cigarette smoke.

Short term, carbon monoxide accumulation in red blood cells will definitely increase the aviator’s susceptibility to the effects of hypoxia at altitude. Keep in mind that carbon monoxide once adsorbed by the blood cells can hang around for days. Data on long term effects of marijuana smoke is lacking but I’ll bet you dollars to doughnuts they’re not good. I think it’s reasonable to assume we will begin to see the appearance of emphysema and chronic bronchitis in long-term marijuana smokers as the Baby Boomers slip into their Golden Years.

Likewise, it would be no surprise if an increased incidence of lung cancer and other forms of malignancy pop up in this group. Now those of you who are compulsive Google-searchers will turn up some studies suggesting an anti-tumor effect for weed.

Indeed, studies in mice and rats have shown that cannabinoids may inhibit tumor growth by causing cell death, blocking cell growth, and blocking the development of blood vessels needed by tumors to grow. Other studies have shown that cannabinoids may be able to kill cancer cells while protecting normal cells. Keep in mind two things: 1) these are mice and rats; 2) the investigators are using pure tetrahydrocannabinol or its break-down products, not the tar and nicotine-laden stuff you suck into your lungs when you smoke it.

Marijuana addiction is seen far less frequently than with alcohol, narcotics or stimulants. However the number of people seeking treatment for dependence has been increasing in recent years. Currently there are no drugs approved by the Food and Drug Administration for addressing marijuana dependence. The mainstay of treatment is talk therapy and support groups structured after the Alcoholics Anonymous model.

So that’s the scoop on weed. In spite of its ubiquity, the FAA still takes a very dim view of marijuana use. It is of course your choice or “lifestyle decision”. Just make sure you understand the implications. For a career in aviation, they are all bad!

Fly wisely. See you next month!

As always, comments, questions and suggestions are welcome: jdlakin@mnallergyclinic.com.